Liquids, an particularly volatile liquids, containing one or more active materials wherein the active material comprises at least one of: a fragrance; an insecticide; a fungicide; a pesticide; a sanitising material; and/or a pharmaceutical are delivered within the domestic environment via a variety of mechanisms. Devices are available with heaters disposed therein to increase the rate of emanation from a surface saturated with the liquid, such a surface could be a wick saturated with a fragranced liquid and the heater is located adjacent the wick surface and nearby a chimney to heat the liquid on the wick surface and cause it to more readily evaporate and disseminate into the surrounding environment through the chimney.
Alternatively such liquids can be loaded in an aerosol canister, the canister holds the liquid under pressure and when the canister valve is opened the liquid is forced out. The liquid is provided with a propellant which evaporates inside the canister to maintain an even pressure and, outside the canister, assist with the mechanical break up of the liquid by evaporating rapidly. Suitable propellants include volatile hydrocarbons such as propane, butane or isobutane.
Aerosols generally provide a satisfactory spray performance but since they require manual operation by a user, they are not considered to be particularly convenient for routine use. Automatic aerosol activation devices exist for operation with metered dose aerosols. These devices are operable to periodically actuate the aerosol to cause a dose of the liquid to be sprayed.
Whilst the automation of the device overcomes the problem of manual operation of a canister, the use of aerosols containing such propellants is becoming increasingly less desirable since these volatile hydrocarbons carry the disadvantage of being flammable, the rising cost of oil is rendering them increasingly expensive and they also carry the further disadvantage of being an atmospheric source of carbon which is deemed to not be environmentally sensitive.
In the field of air freshening it is generally preferred to use a fragranced liquid/air freshening liquids comprising several components. These components often possess different volatilities which can lead to emission problems. The effect of fractionation can be particularly pronounced for powered emanation devices using a heater to effect emanation such as a plug-in emanation device or the like.
In such device a build-up phenomenon can occur in which an accumulation of volatile liquid components with the lowest comparative volatilities can occur leading to an undesirable non-uniform emanation profile for the liquid. This phenomenon can produce an olfactory sensation wherein the fragrance character changes over the course of emanation of a quantity of the fragranced volatile liquid such that the ‘high notes’ of a fragrance are the first to be evaporated when the wicking material is first exposed to the fragranced liquid, and the ‘low notes’ are evaporated thereafter.
Accordingly, it is an object of the present invention to provide a device that is capable of addressing the abovementioned performance drawbacks and other drawbacks that will be appreciated by a person skilled in the art.